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Runway excursion by DL MD-80

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Runway excursion by DL MD-80

Old 4th Apr 2015, 13:03
  #201 (permalink)  
 
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So if you pull in too much left reverser and are headed for the left edge of runway you wouldn't piss away your time removing the force that is putting you there. You would cancel all reverse and use braking on an icy runway to regain directional control and stop?

Why not correct the improper reverse usage immediately? Yes, it would be better to use proper reversers to start with but they were already past that stage. If differential reverse usage is so confusing just practice it once in a while on a dry runway until it isn't. That's what us old school guys did and it ain't that hard.

Last edited by bubbers44; 4th Apr 2015 at 13:11. Reason: addition
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Old 4th Apr 2015, 13:15
  #202 (permalink)  
 
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bubbers 44

the idea of reins of a horse is brilliant

getting use to the idea of pulling back on the TR levers and say WHOA and then if you are not stopping straight pull to the side you want to go to.


other should remember this and also the idea of using normal thrust to steer plane in aerodynamic control emergency in flight
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Old 4th Apr 2015, 13:34
  #203 (permalink)  
 
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The NTSB report cited by JammedStab referred to a 1980 flight test accident that occurred while validating the abnormal procedure for loss of hydraulics.

However changes to T/R operation were expanded to include normal landings:





When did FAA/Boeing/McD change the procedure to permit the use asymmetric reverse?
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Old 5th Apr 2015, 02:40
  #204 (permalink)  
 
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so, in other words

the md88 crew didn't have the nose gear on the ground, did not go to idle reverse and verify and then go to 1.6 epr max

no need to talk about using assymetric reverse for anything, but they put the deployment of reverse OVER AND ABOVE directional control.

this of course is wrong.

ON the early DC9s, you could put reverse out before nose wheel was on ground. THE MAIN reason the 80 series didn't do this is the reversers would scrape the runway with the nose wheel too far off the runway.
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Old 5th Apr 2015, 07:28
  #205 (permalink)  
 
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'Bubber's' read what Zeffy posted.


That sums it up.
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Old 5th Apr 2015, 10:41
  #206 (permalink)  
 
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Zeffy's simplified use of reverse to maintain directional control would work most of the time if they never used assymetrical reverse to get into that situation in the first place. When the deviation first occured it could have easily been stopped by reducing left reverse immediately followed by reduction of all reverse until rudder control was reestablished. Now you are still on the runway, not off the side waiting for rudder effectiveness to return.
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Old 5th Apr 2015, 15:22
  #207 (permalink)  
 
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Naturally, if normal directional control, in accordance with the flight manual, is working, use it.

But if you are out of control, and normal directional control is not working, you have to be able to at least consider the use of assymetric thrust. reverse or otherwise.

I recall the explanation for the information about not using assymetric reverse thrust from our director of training. Quite simply, if you are not good at it, it won't go well. There is a real "TOUCH" to using thrust reverse. The idea of thinking of it like the reins of a horse is excellent. But if you are not adapt at it, you will make things worse. So think about it, try it in the sim, get your mind working on the REIN thing and you will have an additional tool to keep your plane safe.

I DO WONDER which pilot was flying? Quite frankly, if you are right handed, it is easier to use the throttles, reverse levers with the right hand (as if you are captain), than using your left hand,(as if you are copilot)

IF I had to bet, I would bet the copilot was flying. But if anyone knows who was really flying I would be interested in finding out.
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Old 6th Apr 2015, 04:56
  #208 (permalink)  
 
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Don't know about 'reining in horses' but I do believe in following the flight manual.


In four years of flying the MD80 I never had a directional 'issue' like this one but we never used that much reverse, especially on a contaminated runway.


When you start talking about manipulating reverse to straighten out an aircraft that's starting to go sideways you're kidding yourself.


The reason you're having this problem is because of rudder blanking, this is what you need to eliminate immediately.


That's why the manufacturer recommends reducing reverse immediately and that's what you should do.
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Old 6th Apr 2015, 14:57
  #209 (permalink)  
 
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When you start talking about manipulating reverse to straighten out an aircraft that's starting to go sideways you're kidding yourself.
Spot on!
You don't horse around with the reversers on the MD 80.
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Old 6th Apr 2015, 18:13
  #210 (permalink)  
 
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Fast Cruiser, MD80 evacuation checklist contains ; "Spoilers retract"
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Old 6th Apr 2015, 18:24
  #211 (permalink)  
 
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Is not the reverser still going to blank out the rudder in the direction you need to go?
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Old 6th Apr 2015, 19:49
  #212 (permalink)  
 
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The proof of the pudding is in the eating.

The plane in question went to the left.

The thrust reverse was assymetric.

Therefore assymetric reverse will provide directional control

HOWEVER, it might have worked out better in this situation to use more reverse on the right than the left.

Assymetric thrust in many situations can help you. YOU HAVE TO KNOW WHEN AND WHERE to use it.

Sioux City, assymetric forward thrust allowed for some steering to a disabled plane and allowed some survivors!

In a rudder hardover, if you cannot control things with the book procedures, different thrust levels could provide some degree of control.

IN a landing situation , if the conventional aerodynamic controls are not sufficient, if nosewheel steering is not sufficient, then at least consider steering with reverse thrust as a possible solution.

DO we go around the country steering the plane with assymetric thrust? NOPE. IT is something to keep in your bag of tricks, in your skill set if you will, to be used when the fecal matter hits the oscillating ventilator .
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Old 6th Apr 2015, 20:39
  #213 (permalink)  
 
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Why on earth would anyone want a serving of that pudding?

FAA and the manufacturer both caution against the use of excessive reverse thrust due to rudder blanking.

Why would a pilot want to nullify the effectiveness of a primary aerodynamic control with improper (per the guidance of both the mfg and the FAA) application of reverse thrust?

And subsequently try to use more of the same ill-advised technique to salvage the self-induced situation?

The preceding aircraft (landing 3 minutes earlier than the accident airplane) was also an MD-88 operated by the same carrier. They landed safely.

Would there be any "pudding" to be derived from that information?
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Old 6th Apr 2015, 23:09
  #214 (permalink)  
 
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zeffy, apparently you don't get it.

I AM SAYING the guys made a mistake, they didn't follow the procedures, 1.3 epr etc.


BUT ONCE you are out of control why not try to salvage it?

IF you had landed on centerline, on speed, gotten nose wheel on the ground and went to 1.3 epr and then lost control, cancelled reverse and you were still headed for disaster would you:

1. Attempt assymetric thrust to regain control

2. give up and go along for the ride


I AM not saying land and fool around with reverse thrust assymetry

I AM SAYING land and maintain directional control, but if that fails you might try what I've been talking about.
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Old 7th Apr 2015, 00:42
  #215 (permalink)  
 
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I love it. Pilots that know MORE than the manufacturers who designed and built the airplane.

I'm not sure if this is what happened at LGA but anytime you get the airplane out of alignment with the centerline on a contaminated runway, you have a component of that reverse thrust that is directly pushing the aircraft off the side of the runway. If there is a crosswind and the aircraft has weathervaned, that reverse thrust is just going to make it worse - whether it is applied asymmetrically or not. That is why it is not recommended to try to salvage the situation with asymmetric reverse thrust.
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Old 7th Apr 2015, 01:13
  #216 (permalink)  
 
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I love it, people on PPRuNe who don't understand english.
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Old 7th Apr 2015, 10:47
  #217 (permalink)  
 
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Amazing that the SPECIFIC manufacturers recommendations are being second guessed by people who have probably never flown the MD80.


Even if rudder blanking wasn't the main culprit here the difference in epr was not that significant, furthermore we're not dealing with wing mounted engines that have a lot of asymmetric affect to either contribute to or 'recover from' the sideways drift.


If you start going sideways you reduce or cancel reverse, that's what MD recommends , they were right and for a good reason, its far more important to get the rudder in clean air and working again than monkeying around with asymmetric reverse, that will just get you in more trouble.
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Old 7th Apr 2015, 13:48
  #218 (permalink)  
 
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As previously stated, manipulating reverse thrust can bite you. The manufacturer doesn't want to share any liability for improper use so simply says to cancel reverse thrust for directional control problems. Aviation today is made as simple as possible so low time pilots can pass their check rides and get in the right seat as soon and as cheaply as possible.

Learning the finer points of piloting comes with experience and hopefully someone who will share with you what he has learned.

An olympic figure skating champion doesn't get there by reading the manual on how to use her skates, does she?
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Old 7th Apr 2015, 17:08
  #219 (permalink)  
 
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Originally Posted by bubbers44 View Post
...Learning the finer points of piloting comes with experience and hopefully someone who will share with you what he has learned.
So, at what point in a pilot's career does s/he attain the professional standing to disregard operating advice from the certification authorities and manufacturers?

Does the carrier issue a frame-able "maximum supreme aviation yoda" certificate? -- or are other methods/credentials used to provide dispensation from published crew operating guidance?

And how does testing or experimenting with the use of asymmetric reverse in MD-80 series on dry pavement prove that the technique will work just fine when the surface is slick?
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Old 7th Apr 2015, 17:29
  #220 (permalink)  
 
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Ironic that the guys advocating the asymmetric reverse thrust in direct contravention of all guidance from companies, manufacturers and other specialists, make comparison to using reigns. Confessions of a cowboy...
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